/*
FUNCTION
	<<memchr>>---find character in memory

INDEX
	memchr

ANSI_SYNOPSIS
	#include <string.h>
	void *memchr(const void *<[src]>, int <[c]>, size_t <[length]>);

TRAD_SYNOPSIS
	#include <string.h>
	void *memchr(<[src]>, <[c]>, <[length]>)
	void *<[src]>;
	void *<[c]>;
	size_t <[length]>;

DESCRIPTION
	This function searches memory starting at <<*<[src]>>> for the
	character <[c]>.  The search only ends with the first
	occurrence of <[c]>, or after <[length]> characters; in
	particular, <<NUL>> does not terminate the search.

RETURNS
	If the character <[c]> is found within <[length]> characters
	of <<*<[src]>>>, a pointer to the character is returned. If
	<[c]> is not found, then <<NULL>> is returned.

PORTABILITY
<<memchr>> is ANSI C.

<<memchr>> requires no supporting OS subroutines.

QUICKREF
	memchr ansi pure
*/

#include <section_config.h>
#include <basic_types.h>
#if defined ( __GNUC__ )
#include <_ansi.h>
#endif
#include <string.h>
#include <limits.h>

/* Nonzero if either X or Y is not aligned on a "long" boundary.  */
#define UNALIGNED(X) ((long)X & (sizeof (long) - 1))

/* How many bytes are loaded each iteration of the word copy loop.  */
#define LBLOCKSIZE (sizeof (long))

/* Threshhold for punting to the bytewise iterator.  */
#define TOO_SMALL(LEN)  ((LEN) < LBLOCKSIZE)

#if LONG_MAX == 2147483647L
#define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
#else
#if LONG_MAX == 9223372036854775807L
/* Nonzero if X (a long int) contains a NULL byte. */
#define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
#else
#error long int is not a 32bit or 64bit type.
#endif
#endif

#ifndef DETECTNULL
#error long int is not a 32bit or 64bit byte
#endif

/* DETECTCHAR returns nonzero if (long)X contains the byte used
   to fill (long)MASK. */
#define DETECTCHAR(X,MASK) (DETECTNULL(X ^ MASK))

LIBC_ROM_TEXT_SECTION
_LONG_CALL_
void *_memchr(const void *src_void, int c, size_t length)
{
	const unsigned char *src = (const unsigned char *) src_void;
	unsigned char d = c;

#if !defined(PREFER_SIZE_OVER_SPEED)
	unsigned long *asrc;
	unsigned long  mask;
	u32 i;

	while (UNALIGNED(src)) {
		if (!length--) {
			return NULL;
		}
		if (*src == d) {
			return (void *) src;
		}
		src++;
	}

	if (!TOO_SMALL(length)) {
		/* If we get this far, we know that length is large and src is
		   word-aligned. */
		/* The fast code reads the source one word at a time and only
		   performs the bytewise search on word-sized segments if they
		   contain the search character, which is detected by XORing
		   the word-sized segment with a word-sized block of the search
		   character and then detecting for the presence of NUL in the
		   result.  */
		asrc = (unsigned long *) src;
		mask = d << 8 | d;
		mask = mask << 16 | mask;
		/*
		* SVACE-UNREACHABLE_CODE : It was depends on the chip architecture is 32bit or 64bit and the #define LBLOCKSIZE (sizeof(long)) value set by the user
		* Realtek: To cover all architecture RTK solution
		*/
		for (i = 32; i < LBLOCKSIZE * 8; i <<= 1) {
			mask = (mask << i) | mask;
		}

		while (length >= LBLOCKSIZE) {
			if (DETECTCHAR(*asrc, mask)) {
				break;
			}
			length -= LBLOCKSIZE;
			asrc++;
		}

		/* If there are fewer than LBLOCKSIZE characters left,
		   then we resort to the bytewise loop.  */

		src = (unsigned char *) asrc;
	}

#endif /* not PREFER_SIZE_OVER_SPEED */

	while (length--) {
		if (*src == d) {
			return (void *) src;
		}
		src++;
	}

	return NULL;
}
